[alsa-devel] Selecting correct input device port.

[Raymond Yau]

2014-10-30 下午12:38 於 "dE" <de.techno at gmail.com> 寫道：
>
> On 10/29/14 13:06, Takashi Iwai wrote:
>>
>> At Tue, 28 Oct 2014 09:57:18 +0530,
>> dE wrote:
>>>
>>>
>>> As I learn't in this mailng list, a device can typically handle only one
>>> stream at a time unless it supports hardware mixing which's exposed via
>>> subdevices in ALSA
>>>
>>> What does subdevice mean for input device?
>>
>>
>> When a device can do multiplexing, the driver can give multiple
>> substreams (= subdevices).
>>
>>> Do they mark physical ports
>>> for input? If not how do I record from a specific input port?
>>
>>
>> You can pass the subdevice number explicity.  It's -1 as default,
>> which means to select the next free one.
>>
>>> Is it
>>> automatically selected by the card?
>>>
>>> And what's 'input source' in ALSA mixer?
>>
>>
>> It's usually a MUX to select the input source, e.g. line in or mic.
>>
>>
>
> Input source for single subdevice right? I've 3 sub device, does it have
to do anything with the fact that I've 3 input source in alsamixer? Do the
3 input source mark 3 different subdevices?

So far, only those 10 channel hda codecs have three ADC

Due to recent change in snd-hda-intel, if your desktop previously had three
subdevices, the new driver create analog capture device with one subdevice
and alt analog capture with two subdevices